Mr. Rosegrant of the food policy research institute says he foresees “a stronger public relations campaign in the reduction of meat consumption — one like that around cigarettes — emphasizing personal health, compassion for animals, and doing good for the poor and the planet.”

It wouldn’t surprise Professor Eshel if all of this had a real impact. “The good of people’s bodies and the good of the planet are more or less perfectly aligned,” he said.